6100 HV stuck between 28 and 30KV

Hi all, sorry but this 6100 HV is driving me nuts. OK cut down version of
the story so far...
 
a) It's a P329 PCB, the later one with the HV trip.
 
b) it was working but suddenly died.
 
c) Adjusted HV Trip and the HV briefly soars upto 35+KV and then cuts off.
R918 has no effect whatsoever on the HV.
 
d) I replaced D901, ZD901, ZD902, Q901 and Q902, C916, C910 (most caps
actually). After this it's slightly better. On startup it goes upto 28kv
and I get a picture but this is obviously still too high. Eventually it
eventually cuts off as the HV creeps upto around 30KV.
 
 
OK does anyone have any other ideas as to what may be causing this? I
measured R918 and it seems fine. It now has a slight effect on the HV
(barely perceptable on the HV probe).
 
 
Any help much appreciated!
 
 
Cheers,
 
Dan

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Received on Thu Feb 23 17:39:27 2006